diff hgext3rd/topic/stack.py @ 2939:7759d040d48d

topic: provide more information when behind count cannot be computed

The behind count has been confusing for various user and the associated error
message is even worth. We try to clarify it to see if that helps.

--- a/hgext3rd/topic/stack.py	Fri Sep 15 23:25:38 2017 +0530
+++ b/hgext3rd/topic/stack.py	Sun Sep 17 19:59:25 2017 +0200
@@ -30,6 +30,7 @@
         self._repo = repo
         self.branch = branch
         self.topic = topic
+        self.behinderror = None
         if topic is not None and branch is not None:
             raise error.ProgrammingError('both branch and topic specified (not defined yet)')
         elif topic is not None:
@@ -166,7 +167,9 @@
                 return len(self._repo.revs("only(%d, %ld)", dest, minroot))
             except error.NoMergeDestAbort:
                 return 0
-            except error.ManyMergeDestAbort:
+            except error.ManyMergeDestAbort as exc:
+                # XXX we should make it easier for upstream to provide the information
+                self.behinderror = str(exc).split('-', 1)[0].rstrip()
                 return -1
         return 0
 
@@ -236,7 +239,8 @@
     else:
         if data['behindcount'] == -1:
             fm.plain(', ')
-            fm.plain('ambigious rebase destination', label='topic.stack.summary.behinderror')
+            fm.plain('ambigious rebase destination - %s' % data['behinderror'],
+                     label='topic.stack.summary.behinderror')
         elif data['behindcount']:
             fm.plain(', ')
             fm.plain('%d behind' % data['behindcount'], label='topic.stack.summary.behindcount')
@@ -331,5 +335,6 @@
     data['troubledcount'] = current.troubledcount
     data['headcount'] = len(current.heads)
     data['behindcount'] = current.behindcount
+    data['behinderror'] = current.behinderror
     data['branches'] = current.branches
     return data